Method of producing polyurethanes



United States Patent O 3 Claims. c1. 2602.5)

This is a division of pending application Serial No. 19,524, filed'April 4, 1960, now U.S. 3,127,404, issued March 31, 1964.

The present invention relates to molecular addition compounds of diazabicyclo-octane and compositions including the same, and their use as catalysts and promotors in condensation reactions, particularly in the formation of polyurethane plastics and foams.

While the synthesis of diazabicyclo-octane in small amounts had been known in earlier literature, it is only recently that this compound has become available in commercial quantities. It can be prepared in plant operation by the methods described in application Serial No. 628,723 of December 17, 1956 (now U.S. Patent No. 2,937,176 issued May 17, 1960). Because of its versatility as a catalyst coupled with high activity and balanced selectivity, this compound has found extensive use as a catalyst in the preparation of polyurethane elastomers, foams, and plastics made by reaction of organic diisocyanates with long chain polyols, including polyether and/or polyester compounds of 800 to 6000 molecular weight having reactive groups, particularly hydroxyl groups. Various formulations employing diazabicyclooctane as catalyst in rigid and flexible foams, both of the poleyster and polyether types, have been described in the literature; see, for example, Aylesworth et al. in Mod- 'ern Plastics, 1958, pages 145-154; the article in Chemical Processing of February 1959, pages 53 and 54; and Erner et al., One Shot Urethane Foams, in Modern Plastics, February 1960, page 107. For specialized uses, formulations employing diazabicyclo-octane in association with other catalysts of the tertiary amine types or with organic tin compounds or tin soaps have been described in technical bulletins circulated to the industry. The physical and chemical properties of diazabicyclo-octane have been reported in Industrial and Engineering Chemistry of October 1959, at page 1299, and in the Journal of Chemical and Engineering Data of October 1959, at page 334. V

In certain systems for forming flexible or rigid foams, it is desirable to slow down the rate of reaction between the isocyanate and the long chain polyol and/ or the rate of release of the gaseous blowing agent (CO produced by the reaction of isocyanate with water. Among suggested possibilities for accomplishing these ends, blocking of the activity of the catalyst component to obtain delayed catalytic reaction has in some selected instances shown good promise. Thus, in connection with diazabicyclo-octane as catalyst, the formation of certain molecular addition compounds thereof has already been described in copending U.S. application of William E. Erner et 211., Serial No. 792,479 of February 11, 1959, now U.S. Patent 3,037,026 of May 29, 1962.

The present invention relates to new composition of matter having improved advantages as catalyst in polyurethane formulations.

In accordance with the present invention, such new compositions of matter are formed by admixing or reacting diazabicyclo-octane with 1) solutions of boric acid in a short chain polyhydric alcohol having at least two of the hydroxyl groups on adjacent carbon atoms, or

3,193,515 Patented July 6, 1965 with (2) the ester acids or partial esters formed by condensation of boric acid with such short chain polyhydric alcohols containing hydroxyl groups on adjacent carbon atoms. Specific examples of such blocking or retarding reagents for diazabicyclo-octane include the familiar glycol-boric acid and glycerol boric acid complexes, or solutions of boric acid in glycol or glycerol.

In forming addition compounds with diazabicyclo-octane, it is not necessary to employ the formed or isolated polyhydric alcohol-boric acid complex or partial ester, but the reaction mixture or solution obtained can be employed directly as such. For example, glycol-boric acid of the suggested structural formula mo o 0-43112 and forming a comparatively strong acid as a result of the available proton. To drive the reaction toward completion conditions need to be employed such that the released water is removed from the field of reaction. On the other hand, if the water is-not removed, an equilibrium composition is obtained containing an amount of ester acid (partial ester) depending upon the temperature, proportions of reactants, and other conditions of the reaction. In association with diazabicyclo-octane for the purposes of the present invention, there may be employed those solutions or reaction mixtures containing unremoved Water and unreacted components, in addition to any acid complex or partial ester formed,

Since alcohols, including polyhydric alcohols, will react with isocyanate it is preferred, for convenience, to employ catalyst solutions containing the diaza-bicyclo-octane-boric acid-polyol addition complex, which solutions do not have too great an excess of available hydroxyl groups; otherwise the proved polyurethane formulations, which have been worked out largely empirically, would need to be modified to compensate for the hydroxyls presout which would compete in the alcohol-isocyanate reaction; For reaction with the diazabicyclo-octane, accordingly, there are preferably employed those products or solutions formed by dissolving not substantially less than t mol of boric acid per mol of glycerine or glycol; excess (unreacted) boric acid is not of itself detrimental except for unnecessarily loading the system with extraneous products. Generally it will be necessary to heat H Anlon (horate complex) as with one or both of the bridgehead N atoms 'quaternized and complexed, which can conveniently be dissociated at a desired stage in the formation of the polyurethane foam by the release of exothermic heat in the polyurethane foam reaction or by chemical reaction with components of the polyhydric alcohol-boric acid solution. In fact, a-slight controlled excess of free tertiary. amine may be desirable in certain formulations to'promote the initial urethane condensation reaction between the isocyanate and alkyl. ester resin or long chain polyol, additional free catalytic .tertiary amine, being subsequently released from the blocked addition compound during creaming, rising, or.

,7 Example [I A foam formulation similar to that of the previous example was employed, but substituting .a mixture of glycolboric acid-diazabicyclo-octane for the glycerine mix.

This mixture was prepared from 2 mols of glycol to 1 mol of boric acid and 1 mol of diazabicyclo-octane added to other stage ofthe foam forming process. The presence 7 of a small amount of free and releasable water in the catalyst composition should be taken into consideration; 7

observed that in using the-described catalyticsolutions' comprising the formed or potential glycol or other polyol.

complexes of boric acid, as water is used up in the blowing reaction, additional esterificationor complex forma-' tion may take place between free boric acid and vicinal 'hydroxyl groups present, thereby furthe'r moderating or modifying the catalytic activity of the diazabicycl-o- Example I (a) 92 parts by weight of glycerine were admixed with 38 parts by weight of boric acid and heated on a hot plate the solutionwith stirring. In the foam formulation there was employed 1.33 parts of the glycol-boric acid solution of diazabicyclo-octane to provide'0.5 part of diazabicyclo octane per 100 parts of polyols.

The mixture creamed in seconds and had a rise time of 150 seconds, producing a foam of good texture, welldistributed closed-cell structure and low density.

Delayed action catalysts, such as those of the present invention, find use not only in machine-mixed formulations for obtaining a desirably high rise, but also for foamed-in-place compositions, in which deep pour or delayed creaming is advantageous. While in the examples above the boric acid-polyol complex addition compounds of diazabicyclo-octane showed delayed activity, in certain formulations these addition compounds may exhibit acceleration of activity. Such acceleration of foaming and setting is particularly valuable in spray coating with exoctane by reactionof the acid complex with diazabicycloocta'ne.- r

to 180 F. with stirring. After cooling the reaction mixture to approximately 100 F., there was stirred into the solution 55 parts by-weight of diazabicyclo-octane. These proportions were based on using for each mol of glycerine approximately /2 mol of boric acid and about /2 molof diazabicyclo-octane.

(b) The obtained reaction liquid which was in the form of a substantially clear solution was employed in a hand-mixed formulation for the preparation of a flexible polyurethane foam in the following proportions:

Glycerol-boric acid-diazabicyclo-octane mixture from (a) to provide about 0.5 p.b.w. diazabicyclooctane 1.6 Condensation product of glycerine with propylene oxide of about 3000 M.W. having a hydroxyl number of about 56.

The long chain polyols and diisocyanate were.v pre- Parts by Weight Triol LG56 1 40 Polypropylene glycol (M.W. circa 2000) 60 j Toluene diisocyanate (TDI 80-20) 37 Silicone oil 1 a Water 2.9

mixed with mechanical agitation for about aminute, after which the catalyst, water and silicone oil were added,

stirred and poured into a suitable mold. I

The above mixture produced a good foam of uniform texture which was tack-free in about ten minutes after rising. The cream time was about seconds and the rise time about 300 seconds. Using free diazabicyclooctane in equivalent amount in an otherwise identical formulation in hand-mix operation, the cream time is about 20 seconds and the rise time about 120 seconds.

The indicated delay in cream. time obtained'with the traneous' gas blown rigid polyurethane foams. In these Y formulations deep pour and height of rise are generally of less important consideration than the ability of the mix to foam almost instantaneously on leaving the spray gun and rise in comparatively short time without running.

In the typical rigid foam spray coating formulations at least a portion of the high molecular weight polyester or polyether is employed as a prepolymer or quasi prepolymer, produced by reaction of the hydroxy compound polyol, catalyst and gaseous blowing agent, which admixtureis spray discharged through a separate nozzle at a controlled ratio to the prepolymer mixture. The two sprayed solutions become mixed on contact after their discharge from the nozzles and are deposited in reacting admixture on the surface to be coated, whereon they form a rising foam.

" Example III 7 Parts by Component A: weight Prepolymer 94 Trichlorofluoromethane 34 Component B:

Polyol resin 69.4 Diazabicyclo-octane 31% in mixture with glycerine-boric acid 1.6 Silicone oil 1.0

Example IV' A formulation that may be employed for a rigid foam for coating by spray application is as follows:

. Parts by Component A: Weight Prepolymer Silicone oil 0.5

Component B:

Polyol 44 Trichlorofluoromethane 25 Catalyst 0.6

Providing 0.6 part of diazabicyclo-octane as the active part from the glycol-boric acid solution of diazabicyclo-octane.

Depending upon the properties desired in the sprayed coating, the weight ratio of the B component to the A component may be varied from about 0.65 to 0.75. The above formulation is based on using a prepolymer providing about 25% excess-NCO for reaction with the polyol in Component B. The quantity of polyol, used chiefly as cross-linking agent, in Component B is, of course, that needed to react with the isocyanate. The specific quantity as given in the formulation above is based on using a tetrahydroxy compound of about 240 molecular weight (e.g., tetraethanol ethylene diamine).

Example V A formulation for a low density open-celled flexible ester type foam is as follows:

Parts by weight Hydroxy polyester resin of dimer acid 1 100 Tolylene diisocyanate (100% of theoretical) 34.6 Suficient complex to furnish diazabicyclo-octane 0.4 Water 2.9

Made from polymerized C18 unsaturated fatty acids (1 mol) and diethylene glycol (1.5 mols), having a hydroxy number of 74 and acid value of 1.8.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

What is claimed is:

1. In the method of producing cellular polyurethane by reacting a precursor composition comprising tolylene diisocyanate and a hydroxly-containing compound selected from the group consisting of a polyether and a polyester, the hydroxy-containing compound being present in a quantity by weight larger than the quantity by weight of tolylene diisocyanate, said precursor compositon containing a blowing agent and also containing 1,4-diaza(2.2.2)bicyclooctane in a concentration of about 0.5% of said hydroxylcontaining compound, the improvement which consists essentially of delaying the action of a portion of the 1,4- diaza(2.2.2)bicyclooctane catalyst by including such portion of the 1,4-diaza(2.2.2)bicyclooctane as a composition prepared by reacting a lower polyol having alcoholic hydroxyl groups on adjacent carbon atoms with an amount of boric acid corresponding to at least one-half mol of boric acid per mol of polyol to prepare a glycolborate acid, and reacting the glycolborate acid with at least onehalf mol of 1,4-diaza(2.2.2)bicyclooctane per mol of acid to prepare a glycolborate salt-like addition product of 1,4-diaza(2.2.2)bicyclooctane.

2. In the method of producing cellular polyurethane by the reaction occurring in a precursor composition comprising an organic diisocyanate, a hydroxyl-containing compound selected from the group consisting of a polyether and a polyester, and a blowing agent, said reaction being catalyzed by the presence in said composition of a catalytic amount of 1,4-diaza(2.2.2)bicyclooctane, the improvement which consists essentially of delaying the action of at least a portion of the 1,4-diaza(2.2.2)bicyclooctane by including such portion of the 1,4-diaza(2.2.2) bicyclooctane as a composition prepared by reacting a lower polyol having alcoholic hydroxyl groups on adjacent carbon atoms with an amount of boric acid corresponding to at least one-half mol of boric acid per mol of polyol to prepare a glycolborate acid, and reacting the glycolborate acid with at least one-half of l,4-diaza(2.2.2) bicyclooctane per mol of acid to prepare a glycolborate salt-like addition product of 1,4-diaza(2.2.2)bicyclooctane.

3. The methof of producing a cellular polyurethane composition consisting essentially of the steps of mixing a precursor composition comprising a major molar amount of a mixture of organic diisocyanate, a hydroxyl-containing compound selected from the group consisting of a polyether and a polyester, and a blowing agent, and a catalytic amount of a composition prepared by reacting a lower polyol having alcoholic hydroxyl groups on adjacent carbon atoms with an amount of boric acid corresponding to at least one-half mol of boric acid per mol of polyol to prepare a glycolborate acid, and reacting the glycolborate acid with at least one-half mol of 1,4-diaza(2.2.2) bicyclooctane per mol of acid to prepare a glycolborate salt-like addition products of 1,4-diaza(2.2.2)bicyclooctane, said precursor composition undergoing a transformation into a polyurethane composition possessing improved properties by reason of the delayed action of a portion of the 1,4-diaza(2.2.2)bicyclooctane catalyst.

No references cited.

LEON J. BERCOVITZ, Primary Examiner.

DONALD E. CZAJA, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 193,515 July 6, 196E Rocco L. Mascioli It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 29, for "hydroxy" read hydroxyl line 39, for "hydroxyl" read hydroxylline 41 for "hydroxy-" read hydroxylcolumn 6, line 23, after "onehalf" insert mol line 27, for "methof" read method same column 6, line 40, for "products" read product Signed and sealed this 18th day of January 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. IN THE METHOD OF PRODUCING CELLULAR POLYURETHANE BY REACTING A PRECURSOR COMPOSITION COMPRISING TOLYLENE DIISOCYANATE AND A HYDROXLLY-CONTAINING COMPOUND SELECTED FROM THE GROUP CONSISTING OF A POLYETHER AND A POLYESTER, THE HYDROXY-CONTAINING COMPOUND BEING PRESENT IN A QUANTITY BY WEIGHT LARGER THAN THE QUANTITY BY WEIGHT OF TOLYLENE DIISOCYANATE, SAID PRECURSOR COMPOSITION CONTAINING A BLOWING AGENT AND ALSO CONTAINING 1,4-DIAZA (2,2,2) BICYCLOOCTANE IN A CONCENTRATION OF ABOUT 0.5% OF SAID HYDROXYLCONTAINING COMPOUND, THE IMPROVEMENT WHICH CONSISTS ESSENTIALLY OF DELAYING THE ACTION OF A PORTION OF THE 1,4DIAZA (2.2.2) BICYCLOCTANE CATALYST BY INCLUDING SUCH PORTION OF THE 1,4-DIAZA (2.2.2.) BICYCLOCOTANE AS A COMPOSITION PREPARED BY REACTING A LOWER POLYOL HAVING ALCOHOLIC HYDROXYL GROUPS ON ADJACENT CARBON ATOMS WITH AN AMOUNT OF BORIC ACID CORRESPONDING TO AT LEAST ONE-HALF MOL OF BORIC ACID PER MOL OF POLYOL TO PREPARE A GLYCOLLBORATE ACID, AND REACTING THE GYLCOLLBORATE ACID WITH AT LEAST ONEHALF MOL OF 1,4-DIAZA (2.2.2.) BICYCLOCOTANE PER MOL OF ACID TO PREPARE A GLYCOLLBORATE SALT-LIKE ADDITION PRODUCT OF 1,4-DIAZA (2.2.2) BICYCLOOCTANE. 